State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Ke-yuan Road 4, No. 1, Gao-peng Street, Chengdu, Sichuan, 610041, China.
Neoplasma. 2012;59(6):676-84. doi: 10.4149/neo_2012_086.
Commonly used drugs for the treatment of colon{} cancer patients like CPT-11 shows severe side effects or induces resistance in clinical settings. Thus, we analyzed a combination of PLK1 (polo-like kinase 1)-specific short hair RNA (shRNA), a potent tool to destroy mitosis in cancer cells, together with CPT-11 to enhance drug sensitivity. Cellular proliferation and apoptosis were determined in SW620 colorectal carcinoma cells. Knockdown of cellular PLK1 led to the decreased mRNA and PLK1 protein in RT-PCR and western blot assay. The viability declined (p<0.001) in MTT assay and colony formation assay, and the number of apoptotic cells was clearly increased (p<0.01) in flow cytometric analysis and Hoechst 33258 staining compared with control cells after incubation with PLK1-specific shRNA and SN-38. We found the level of cleaved PARP was also increased in vitro. In vivo, employment of shRNA targeting PLK1 improved the sensitivity to treat SW620 nude mouse model toward CPT-11. The combination therapy inhibited cellular proliferation and promoted apoptosis observed at the percentage of PCNA and caspase3 by immunohistochemistry, accompanied with TUNEL assay. As we expect, the combination treatment delayed tumor growth (p<0.01) and simultaneously reduced tumor weight (p<0.01) compared with control group. Taken together, combination of PLK1-specific shRNA interference with low-dose CPT-11 triggered a antitumor efficacy and represented a potential strategy to treat colon cancer.
在临床环境中，常用于治疗结肠癌患者的药物，如 CPT-11，会显示出严重的副作用或诱导耐药性。因此，我们分析了 PLK1（丝氨酸/苏氨酸激酶）特异性短发夹 RNA（shRNA）与 CPT-11 的联合应用，以增强药物敏感性。我们在 SW620 结肠癌细胞中分析了细胞增殖和细胞凋亡。细胞 PLK1 的敲低导致 RT-PCR 和 Western blot 分析中细胞内的 mRNA 和 PLK1 蛋白减少。MTT 分析和集落形成试验表明细胞活力下降（p<0.001），流式细胞术分析和 Hoechst 33258 染色表明凋亡细胞数量明显增加（p<0.01）。与对照细胞相比，经 PLK1 特异性 shRNA 和 SN-38 孵育后，体外 cleaved PARP 的水平也增加。在体内，PLK1 靶向 shRNA 的应用提高了对 CPT-11 的治疗 SW620 裸鼠模型的敏感性。联合治疗通过免疫组化观察到细胞增殖抑制和 caspase3 表达增加，同时伴随着 TUNEL 检测到的凋亡增加。正如我们所预期的，与对照组相比，联合治疗延迟了肿瘤生长（p<0.01）并同时降低了肿瘤重量（p<0.01）。总之，PLK1 特异性 shRNA 干扰与低剂量 CPT-11 的联合应用触发了抗肿瘤疗效，代表了治疗结肠癌的一种潜在策略。
