Luciani Francesca, Spada Massimo, De Milito Angelo, Molinari Agnese, Rivoltini Licia, Montinaro Annalisa, Marra Manuela, Lugini Luana, Logozzi Mariantonia, Lozupone Francesco, Federici Cristina, Iessi Elisabetta, Parmiani Giorgio, Arancia Giuseppe, Belardelli Filippo, Fais Stefano
Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Nazionale dei Tumori, Milan, Italy.
J Natl Cancer Inst. 2004 Nov 17;96(22):1702-13. doi: 10.1093/jnci/djh305.
Resistance to antitumor agents is a major cause of treatment failure in patients with cancer. Some mechanisms of tumor resistance to cytotoxic drugs may involve increased acidification of extracellular compartments. We investigated whether proton pump inhibitors (PPIs), currently used in the anti-acid treatment of peptic disease, could inhibit the acidification of the tumor microenvironment and increase the sensitivity of tumor cells to cytotoxic agents.
We pretreated cell lines derived from human melanomas, adenocarcinomas, and lymphomas with the PPIs omeprazole, esomeprazole, or pantoprazole and tested their response to cytotoxic drugs in cell death assays. We also evaluated extracellular and intracellular pH and vacuolar-H+-ATPase (V-H+-ATPase) expression, distribution, and activity in PPI-pretreated cells by using western blot analyses, immunocytochemistry, laser scanning confocal analysis, and bioluminescence assays. Finally, we evaluated human melanoma growth and cisplatin sensitivity with or without omeprazole pretreatment in xenografted SCID/SCID mice.
PPI pretreatment sensitized tumor cell lines to the effects of cisplatin, 5-fluorouracil, and vinblastine, with an IC50 value reduction up to 2 logs. PPI pretreatment was associated with the inhibition of V-H+-ATPase activity and increases in both extracellular pH and the pH of lysosomal organelles. PPI pretreatment induced a marked increase in the cytoplasmic retention of the cytotoxic drugs, with clear targeting to the nucleus in the case of doxorubicin. In in vivo experiments, oral pretreatment with omeprazole was able to induce sensitivity of human solid tumors to cisplatin.
Our results open new possibilities for the treatment of drug-resistant tumors through combination strategies based on the use of well-tolerated pH modulators such as PPIs.
对抗肿瘤药物的耐药性是癌症患者治疗失败的主要原因。肿瘤对细胞毒性药物产生耐药性的一些机制可能涉及细胞外区室酸化增加。我们研究了目前用于消化性疾病抗酸治疗的质子泵抑制剂（PPI）是否能抑制肿瘤微环境的酸化并增加肿瘤细胞对细胞毒性药物的敏感性。
我们用PPI奥美拉唑、埃索美拉唑或泮托拉唑预处理源自人黑色素瘤、腺癌和淋巴瘤的细胞系，并在细胞死亡试验中测试它们对细胞毒性药物的反应。我们还通过蛋白质印迹分析、免疫细胞化学、激光扫描共聚焦分析和生物发光测定法评估了PPI预处理细胞中的细胞外和细胞内pH值以及液泡型H⁺-ATP酶（V-H⁺-ATPase）的表达、分布和活性。最后，我们评估了在移植了人黑色素瘤的SCID/SCID小鼠中，有或没有奥美拉唑预处理时人黑色素瘤的生长和顺铂敏感性。
PPI预处理使肿瘤细胞系对顺铂、5-氟尿嘧啶和长春碱的作用敏感，IC50值降低高达2个对数。PPI预处理与V-H⁺-ATPase活性的抑制以及细胞外pH值和溶酶体细胞器pH值的增加有关。PPI预处理导致细胞毒性药物在细胞质中的滞留显著增加，就阿霉素而言，明显靶向细胞核。在体内实验中，口服奥美拉唑预处理能够诱导人实体瘤对顺铂敏感。
我们的结果为通过基于使用耐受性良好的pH调节剂（如PPI）的联合策略治疗耐药肿瘤开辟了新的可能性。
