Imaging and Characterizating Stress responses in vivo with p21 Reporter Mice

化疗的全部潜力在实践中可能受到毒副作用的限制。因此，战略或 干预措施，有效地选择性地保护正常细胞，但不是癌细胞，预计将 增加化疗的治疗窗和临床有效性。已发表文献 表明短期站立的小鼠受到高剂量依托泊苷的保护， 杀死他们的同窝出生的婴儿此外，携带突变的肿瘤细胞可引起肿瘤细胞的组成性激活。 PI3K途径已被证明在生长时对饮食限制的抗生长作用不敏感 作为小鼠的异种移植物。因此，禁食可以通过保护正常的化疗效果来提高化疗的效果。 细胞，但不是癌细胞，从化疗的毒性作用和临床试验目前正在进行 旨在测试在化疗前或化疗期间禁食是否会减少癌症相关的副作用 患者然而，很少有人知道介导的差异反应的分子机制， 与癌细胞相比，正常细胞短期饥饿。使用一种基因工程小鼠， 从内源性p21启动子表达萤火虫荧光素酶，我们观察到p21的有效诱导 表达对短期站立的反应。有趣的是，这发生在代谢器官和p21 表达也被观察到，特别是下丘脑的神经元， 新陈代谢.我们的初步研究还表明，p21保护细胞免受DNA损伤的影响 伊立替康是一种拓扑异构酶1抑制剂，临床上用于治疗某些类型的癌症。因此，实验 本申请中提出的方法将（1）确定通过短期饥饿诱导p21表达是否保护 小鼠免受大剂量化疗和电离辐射的致死效应，（2）识别信号传导 负责响应短期饥饿激活p21表达的途径和（3）确定 如果短期站立可以保护小鼠，但不能保护在这些小鼠中生长的PTEN缺陷前列腺癌， 化疗和放疗。

The full potential of chemotherapy can be limited in practice by toxic side effects. Therefore, strategies or interventions that are effective in selectively protecfing normal cells, but not cancer cells, are predicted to increase the therapeutic window and clinical effectiveness of chemotherapy. Published literature demonstrates that mice subjected to short-term stan/ation are protected from high doses of etoposide that kill their fed littermates. In addition, tumor cells carrying mutations that cause constitutive activation of the PI3K pathway have been shown to be insensitive to the anti-growth effects of dietary restriction when grown as xenografts in mice. Thus, fasting may enhance the effectiveness of chemotherapy by protecting normal cells, but not cancer cells, frcim the toxic effects of chemotherapy and clinical trials are currently being conducted to test whether fasting prior to or during chemotherapy reduces associated side-effects in cancer patients. However, little is known about the molecular mechanisms mediating the differential response of normal cells compared with cancer cells to short-term starvation. Using a reporter mouse engineered to express firefly luciferase from the endogenous p21 promoter, we observe a potent induction of p21 expression in response to short-term stan/ation. Interestingly, this occurs in metabolic organs and p21 expression was also observed, forthe first time, in particular neurons ofthe hypothalamus that regulate metabolism. Our preliminary studies also demonstrate that p21 protects cells from the DNA damaging effects of irinotecan, a topoisomerase 1 inhibitor used clinically to treat certain types of cancer. Thus, experiments proposed in this applicafion will (1) determine if induction of p21 expression by short-term starvation protects mice from the lethal effects of high dose chemotherapy and ionizing radiation, (2) identify the signaling pathway(s) responsible for activating p21 expression in response to short-term starvation and (3) determine if short-term stan/ation protects mice, but not PTEN-deficient prostate cancers growing in these mice, from chemotherapy and radiation therapy.