[摘要] 目的: 探讨长链非编码RNA（lncRNA）浆细胞瘤转化迁移基因1（plasmacytoma variant translocation 1, PVT1）对结直肠癌（colorectal cancer，CRC）顺铂（cisplatin，DDP）化疗敏感性的调控作用及其机制。方法: 收集2006 年4 月至2011 年3 月新乡医学院第一附属医院112 例接受手术切除、经病理确诊CRC患者的癌及癌旁组织标本，从中分别选择各30 例顺铂敏感、顺铂耐药癌及癌旁组织；人CRC细胞系HT29、SW480、HCT116、RKO和LoVo 与正常结肠上皮细胞株NCM460，构建顺铂耐药LoVo/DDP及RKO/DDP细胞。用脂质体2000 分别将siPVT1 和siNC、LV-PVT1 和LV-NC 转染或感染LoVo 和RKO细胞或者LoVo/DDP及RKO/DDP细胞。qPCR检测CRC组织及细胞中lncRNA PVT1 的表达水平。CCK-8 法、流式细胞术、WB实验分别检测敲降PVT1或过表达PVT1 对CRC细胞的增殖、凋亡及凋亡相关蛋白的表达影响。构建无胸腺裸鼠CRC皮下移植动物模型，观察对移植瘤体细胞生长及顺铂耐药的影响。结果: PVT1 mRNA在CRC组织及细胞中lncRNA PVT1 高表达，其表达水平与顺铂耐药呈正相关。敲除PVT1 后，显著降低顺铂耐药的CRC细胞的增殖能力并促进其凋亡（P<0.05 或P<0.01）、降低耐药相关分子MDR1 和MRP1 及抗凋亡相关分子Bcl-2 的表达而增加了促凋亡相关分子Bax 和活化的caspase-3 的表达。过表达PVT1 后，则促进细胞增殖并减少其凋亡（P<0.05 或P<0.01）。体内实验表明，在CRC细胞中过表达PVT1 促进顺铂耐药的形成（P<0.05）。结论: 敲降lncRNA PVT1 表达可显著抑制CRC耐药细胞株的增殖并促进其凋亡，过表达PVT1 可明显促进CRC细胞和动物移植瘤体的生长。PVT1 通过抑制MDR1 和MRP1 的表达，调控内源性凋亡通路，进而增强CRC细胞对顺铂的敏感性。

[Abstract] Objective: To study the regulatory effects and possible mechanism of long non-coding RNA plasmacytoma variant translocation 1 (lncRNA PVT1) on chemotherapy sensitivity to cisplatin (DDP) of colorectal cancer (CRC)．Methods: A total of 112 pairs of matched cancer and adjacent non-cancerous tissues were obtained from the CRC patients who underwent surgical resection in the First Affiliated Hospital of Xinxiang Medical University between April 2006 and March 2011. All specimens were confirmed by pathological examinations. Tumor tissues and corresponding adjacent non-cancerous tissues from 30 cisplatin-sensitive CRC patients and 30 cisplatin-resistant patients were selected. Human CRC cell lines (HT29, SW480, HCT116, RKO and LoVo) and normal colonic epithelial cell line NCM460 were also collected for this study; and DDP-resistant RKO/DDP and LoVo/DDP cell lines were constructed. siPVT1,siNC, LV-PVT1 and LV-NC were transfected into LoVo and RKO cells or LoVo/DDP and RKO/DDP cells using lipofectamineTM2000.The expression of lncRNA PVT1 in CRC tissues and cells was tested by Real-time qPCR. CCK-8 assay, flow cytometry and WB were performed to test the effect of PTV1 knockout or enforcement on cell proliferation, apoptosis and expressions of apoptosis-related roteins,respectively. The CRC subcutaneous transplanted xenograft model was established on athymic nude mice to study the effect of PVT1 over-expression on tumor growth and DDP resistance. Results: PVT1 was highly expressed in the cancer tissues and CRC cells,and its expression was positively associated with cisplatin resistance of CRC. After knockdown of PVT1, the proliferation of cisplatinresistant CRC cells was significantly suppressed, while the apoptosis was significantly enhanced (P<0.05 or P<0.01); Mechanically, the levels of drug resistance-associated molecules, including MDR1 and MRP1, as well as the expression of anti-apoptotic Bcl-2 were significantly downregulated whereas the levels of pro-apoptotic Bax and cleaved caspase-3 were increased in PVT1-silenced DDP-resistant CRC cells. Over-expression of PVT1 reversely increased proliferation and decreased apoptosis of CRC cells (P<0.05 or P<0.01).In addition, PVT1 over-expression in CRC cells significantly promoted DDP-resistance in vivo (P<0.05). Conclusion: Collectively,knockdown of PVT1 expression can significantly suppress cell proliferation and promote apoptosis of DDP-resistant CRC cells. Overexpression of PVT1 can significantly promote the growth of CRC cells in vitro and transplanted xenograft in vivo. PVT1 regulates endogenous apoptosis pathways and further promotes the sensitivity of CRC cells to cisplatin chemotherapy via inhibiting the expressions of MDR1 and MRP1.

河南省高等学校重点科研项目（No.16B330001）