抑癌基因PTEN上游5'UTR区uORFs的识别鉴定及在人脑胶质瘤中的功能研究

Inactivation of tumor suppressive gene PTEN is a critical step in malignant glioma tumorigenesis and progression. Researches revealed that the 5’UTR un-translational region of PTEN gene also have tumor suppressive function, yet the mechanism is unknown. Recent years, some small open reading frame (smORF) have been identified in mammal cells non-coding RNA region, which can code some functional small peptides. Based on bio-informatics, we have identified several potential smORF in PTEN’s 5’UTR region. We have confirmed these smORF could translate some small peptides in malignant glioma cells and these peptides have strong tumor suppressive functions. Transfect the glioma cells with these peptides, the proliferation of glioma cells were inhibited and the cell cycle was trapped. This study is design to: 1. Further recognize and identify whether these peptides are really exist; 2.Whether these peptides have potential clinical values and their biological functions; 3. Explore the possibility of using these peptides as novel anti-glioma drugs. Based on this proposal, we hope to bring the whole new concept of “PTEN 5’UTR region encodes small tumor suppressive peptides” and clarify their molecular mechanism, which will provide a theoretical foundation for future clinical practice.

抑癌基因PTEN失活在恶性胶质瘤发生发展过程中具有重要作用。研究表明PTEN基因5'UTR非编码区也具有重要的抑癌功能，但分子机制未明。近年来，在哺乳动物细胞RNA非编码区域内陆续发现了一些上游开放读码框(uORF)，编码一些功能性小分子多肽。利用生物信息学技术，我们在PTEN的5'UTR非编码区发现了数个潜在的uORF。我们前期首次证实这些PTEN 5'UTR区uORF编码具有抑癌活性的未知小分子多肽：转染这些小分子多肽后，恶性胶质瘤细胞增殖被抑制，细胞周期被阻滞。本研究拟：1)进一步识别并鉴定这些小分子多肽存在客观性2)研究这些小分子多肽在恶性胶质瘤中的临床意义和重要生物学功能 3)初步探索将这些小分子多肽作为新的抗恶性胶质瘤药物的可能性。通过本研究我们希望首次提出PTEN基因5'UTR区uORF编码抑癌小分子多肽的全新概念并阐明其分子机制，为未来将其应用于临床治疗恶性胶质瘤打下基础。

课题组一直致力于寻找一些在胶质中具有调控功能的全新小肽，包括uORFs、dORFs以及lincRNA编码的ORFs。通过核糖体印记测序技术，我们发现了一个在胶质瘤癌和癌旁表达有差异，来源于PTEN基因5`UTR的上游开放读码框编码的一个31个氨基酸的小肽，命名MP31。该小肽定位于线粒并且可以通过与NAD+竞争结合线粒体LDH上的结合位点调控乳酸到丙酮酸的转化，进而抑制GBM的氧化磷酸化最终行使抑癌作用。低浓度的MP31多肽可以进入细胞并抑制胶质瘤干细胞的成瘤能力但是对正常神经干细胞和胶质细胞并没有影响。腹腔注射MP31多肽可以穿透血脑屏障进入脑部，抑制病人来源的肿瘤干细胞裸鼠颅内种植瘤的成瘤能力、明显延长小鼠生存期。综上所述本项目发现了一个全新、安全无毒、可以通过血脑屏障并且能够在胶质瘤中行使抑癌功能的纯天然多肽，为临床脑胶质瘤治疗提供全新的潜在候选药物。