饥饿诱导的 ATM/Chk2/p53 信号通路的激活使癌细胞对顺铂敏感。

BACKGROUND: Optimizing the safety and efficacy of standard chemotherapeutic agents such as cisplatin (CDDP) is of clinical relevance. Serum starvation in vitro and short-term food starvation in vivo both stress cells by the sudden depletion of paracrine growth stimulation. METHODS: The effects of serum starvation on CDDP toxicity were investigated in normal and cancer cells by assessing proliferation, cell cycle distribution and activation of DNA-damage response and of AMPK, and were compared to effects observed in cells grown in serum-containing medium. The effects of short-term food starvation on CDDP chemotherapy were assessed in xenografts-bearing mice and were compared to effects on tumor growth and/or regression determined in mice with no diet alteration. RESULTS: We observed that serum starvation in vitro sensitizes cancer cells to CDDP while protecting normal cells. In detail, in normal cells, serum starvation resulted in a complete arrest of cellular proliferation, i.e. depletion of BrdU-incorporation during S-phase and accumulation of the cells in the G0/G1-phase of the cell cycle. Further analysis revealed that proliferation arrest in normal cells is due to p53/p21 activation, which is AMPK-dependent and ATM-independent. In cancer cells, serum starvation also decreased the fraction of S-phase cells but to a minor extent. In contrast to normal cells, serum starvation-induced p53 activation in cancer cells is both AMPK- and ATM-dependent. Combination of CDDP with serum starvation in vitro increased the activation of ATM/Chk2/p53 signaling pathway compared to either treatment alone resulting in an enhanced sensitization of cancer cells to CDDP. Finally, short-term food starvation dramatically increased the sensitivity of human tumor xenografts to cisplatin as indicated not only by a significant growth delay, but also by the induction of complete remission in 60% of the animals bearing mesothelioma xenografts, and in 40% of the animals with lung carcinoma xenografts. CONCLUSION: In normal cells, serum starvation in vitro induces a cell cycle arrest and protects from CDDP induced toxicity. In contrast, proliferation of cancer cells is only moderately reduced by serum starvation whereas CDDP toxicity is enhanced. The combination of CDDP treatment with short term food starvation improved outcome in vivo. Therefore, starvation has the potential to enhance the therapeutic index of cisplatin-based therapy.

背景：优化顺铂（CDDP）等标准化疗药物的安全性和疗效与临床密切相关。体外血清饥饿和体内短期食物饥饿都会通过突然耗尽旁分泌生长刺激来使细胞紧张。

方法：通过评估增殖、细胞周期分布以及 DNA 损伤反应和 AMPK 的激活，研究了血清饥饿对正常细胞和癌细胞中 CDDP 毒性的影响，并将其与在含血清培养基中生长的细胞观察到的影响进行了比较。在荷瘤小鼠中评估了短期食物饥饿对 CDDP 化疗的影响，并将其与未改变饮食的小鼠中确定的肿瘤生长和/或消退的影响进行了比较。

结果：我们观察到，体外血清饥饿使癌细胞对 CDDP 敏感，同时保护正常细胞。具体来说，在正常细胞中，血清饥饿导致细胞增殖完全停滞，即在 S 期期间 BrdU 掺入耗尽和细胞在细胞周期的 G0/G1 期积累。进一步分析表明，正常细胞中的增殖停滞是由于 p53/p21 的激活，这是 AMPK 依赖性的，并且与 ATM 无关。在癌细胞中，血清饥饿也会减少 S 期细胞的比例，但程度较小。与正常细胞不同，血清饥饿诱导的癌细胞中 p53 激活既依赖于 AMPK 也依赖于 ATM。与单独使用 CDDP 相比，体外联合使用 CDDP 和血清饥饿增加了 ATM/Chk2/p53 信号通路的激活，导致癌细胞对 CDDP 的敏感性增强。最后，短期食物饥饿显著增加了人肿瘤异种移植物对顺铂的敏感性，不仅表现在生长明显延迟，而且在 60%的间皮瘤异种移植物和 40%的肺癌异种移植物的动物中诱导完全缓解。

结论：在正常细胞中，体外血清饥饿诱导细胞周期停滞并防止 CDDP 诱导的毒性。相比之下，癌细胞的增殖仅被血清饥饿适度减少，而 CDDP 毒性增强。CDDP 治疗联合短期食物饥饿改善了体内结果。因此，饥饿有可能提高顺铂为基础的治疗的治疗指数。