Institute of Ultrasonic Engineering in Medicine, Chongqing Medical University, Chongqing, China.
Ultrasound Med Biol. 2011 Jan;37(1):151-9. doi: 10.1016/j.ultrasmedbio.2010.10.009. Epub 2010 Nov 16.
Multidrug resistance (MDR) is the major obstacle to successful chemotherapy of human malignancies and strategies for overcoming MDR phenomena are still unavailable to clinical use. Previous results showed that ultrasound (US) exposure could make MDR cancer cells become more sensitive to anticancer drugs, and the physical parameters of US exposure could adjust the uptake and retention of rhodamine 123 in MDR cells. In this study, we investigated the mechanisms of therapeutic ultrasound as a physical approach to overcoming MDR in a multidrug resistant human hepatocarcinoma cell line (HepG2/ADM). Our results demonstrated that the percentage of P-glycoprotein(+) (P-gp), multidrug resistance-associated protein(+) (MRP) and lung resistance-related protein(+) (LRP) cells was 96.97% ± 2.41%, 20.84% ± 3.12% and 1.16% ± 0.59% in HepG2/ADM cells, and 62.84% ± 3.42%, 10.26% ± 1.18% and 3.05% ± 0.37% in US-exposed HepG2/ADM cells, respectively. A significant decrease in the number of P-gp(+) and MRP(+) cells was observed between US-exposed HepG2/ADM and HepG2/ADM cells (p < 0.05). Using RT-PCR technique, we found that US could significantly downregulate the expression of P-glycoprotein (P-gp) and (MRP) at the mRNA level in HepG2/ADM cells. Compared with the control, the percentage of apoptotic cell death was significantly increased in HepG2/ADM after ultrasound exposure. Using immunocytochemistry, the percentage of Bcl-2(+) and Bax(+) cells was 21.7% and 4.1% in the control, and 18.46% and 8.1% in the US-exposed cells, respectively. The percentage of Bax(+) cells was significantly higher in US-exposed HepG2/ADM cells (p < 0.05), suggesting that US exposure could lead to cellular apoptosis in HepG2/ADM cells. It is concluded that US exposure could reverse MDR in HepG2/ADM cells via decreasing P-gp and MRP levels and their mRNA expressions and increasing expression of Bax protein. It may lead to the development of a novel strategy of using a targeted, noninvasive physical approach for the induction of MDR reversal in cancer cells.
多药耐药（MDR）是人类恶性肿瘤化疗成功的主要障碍，克服 MDR 现象的策略仍不能用于临床应用。先前的研究结果表明，超声（US）照射可以使多药耐药癌细胞对抗癌药物更敏感，并且 US 照射的物理参数可以调节 rhodamine 123 在 MDR 细胞中的摄取和保留。在这项研究中，我们研究了治疗性超声作为克服多药耐药人肝癌细胞系（HepG2/ADM）中多药耐药的物理方法的机制。我们的结果表明，在 HepG2/ADM 细胞中，P-糖蛋白（+）（P-gp），多药耐药相关蛋白（+）（MRP）和肺耐药相关蛋白（+）（LRP）细胞的百分比分别为 96.97%±2.41%，20.84%±3.12%和 1.16%±0.59%，在超声照射的 HepG2/ADM 细胞中分别为 62.84%±3.42%，10.26%±1.18%和 3.05%±0.37%。与 HepG2/ADM 细胞相比，超声照射的 HepG2/ADM 细胞中 P-gp（+）和 MRP（+）细胞的数量明显减少（p<0.05）。通过 RT-PCR 技术，我们发现 US 可以在 HepG2/ADM 细胞中显著下调 P-糖蛋白（P-gp）和（MRP）的 mRNA 水平。与对照组相比，超声照射后 HepG2/ADM 细胞的凋亡细胞死亡百分比明显增加。通过免疫细胞化学，对照组中 Bcl-2（+）和 Bax（+）细胞的百分比分别为 21.7%和 4.1%，而超声照射组中的百分比分别为 18.46%和 8.1%。超声照射的 HepG2/ADM 细胞中 Bax（+）细胞的百分比明显更高（p<0.05），表明 US 照射可导致 HepG2/ADM 细胞发生细胞凋亡。结论：US 照射可通过降低 P-gp 和 MRP 水平及其 mRNA 表达，增加 Bax 蛋白表达，逆转 HepG2/ADM 细胞的多药耐药。这可能为利用靶向、非侵入性物理方法诱导癌细胞多药耐药逆转开辟新策略。
