PVT1在胰腺癌化疗耐药中的作用及分子机制研究

Pancreatic cancer is a malignant tumor with the worst prognosis, its unique biological properties cause the failure of chemptherapy. Increasing the effectiveness of chemotherapy is an urgent problem to be resolved. Preliminary study of this subject by the genome-wide random mutagenesis and related experiments found the close relationship between the gene PVT1 and gemcitabine (GEM) sensitivity, but it is still unclear.PVT1,no protein product, Located in chromosome 8q24. co-amplification was found in a variety of tumors with its upstream neighboring MYC gene which can be directly or indirectly regulated by PVT1. PVT1 and MYC play an important role in tumorigenesis and drug resistance. Maybe PVT1 associated miRNA1204-1209 affect the function of MYC by regulating the expression of PVT1 and change the sensitivity to GEM, So based on our work, through the experiments in vitro and in vivo to know more about the relationship between PVT1 、its associated miRNA and MYC, further Verify the role of PVT1 in the chemoresistance of pancreatic cancer, so we can deeply understand its molecular regularory mechanism to look for the targets of combination therapy and a new strategy for the treatment of pancreatic cancer.

胰腺癌是预后最差的恶性肿瘤之一，由于胰腺癌自身独特的生物学特性导致其对化疗不敏感，提高胰腺癌化疗疗效是亟待解决的问题。在课题全基因组化疗耐药相关基因筛查中发现基因PVT1突变增加胰腺癌对一线化疗药物吉西他滨(Gemcitabine, GEM)的敏感性，但其分子机制尚不清楚。PVT1位于染色体8q24，无蛋白编码产物，与其上游邻近的MYC基因在多种肿瘤中共扩增，且可直接或间接的调节MYC基因的表达，二者与PVT1相关的miRNA1204-1209在肿瘤发生及化疗耐药中起重要作用。由此推测miRNA1204-1209可能通过对PVT1、MYC基因功能的调节，影响胰腺癌对GEM的敏感性，遂通过体外、体内实验进一步验证PVT1在胰腺癌化疗耐药中的作用，深入了解其调控网络的分子机制，寻找联合治疗的靶点，为胰腺癌的治疗提供新的策略。

吉西他滨作为胰腺癌一线化疗药物。然而目前临床疗效较差，吉西他滨化疗耐药的分子机制尚不清楚。方法：我们使用qRTPCR（QRT-PCR）分析PVT1在胰腺癌细胞系中的表达的表达； 微小RNA模拟物或抑制剂的转染过表达或抑制PVT1；吉西他滨药物敏感性检测是通过CCK-8，细胞凋亡和细胞周期测定解决；靶向microRNA验证通过荧光素酶报告分析、免疫印迹及免疫组化。全面分析PVT1及其编码RNA和吉西他滨的化学敏感性之间的相关性。结果：敲低细胞PVT1的表达可有效增强吉西他滨的抑制作用。研究中发现miR-1207 pair（miR-1207-5p/miR-1207-3p）在调控吉西他滨化疗敏感性中功能最为显著。miR-1207 pair过表达与敲低显示，miR-1207 pair可以显著影响胰腺癌细胞内源性SRC与RhoA的表达水平，进一步证实SRC/RhoA是miR-1207 pair的直接功能靶基因。吉西他滨亦可以诱导Drosha与DGCR8的表达上调，促进PVT1加工为成熟的miRNA，抑制相关oncogenic 信号通路，发挥抑癌作用。结论：我们的发现可能是胰腺癌化疗耐药新的关键机制之一。