Redox Biology of Quiescent Normal Fibroblasts and Epithelial Cancer Progression

描述(申请人提供)：癌症发病率随年龄呈指数增长，表明共同的机制对这两个生物学过程都有贡献。一种这样的机制被认为是氧化应激，这是由于产生活性氧物种(如O2代谢产生的ROS和H2O2)和它们被抗氧化剂网络清除之间的不平衡。大多数衰老研究集中在了解调控复制寿命(Hayflick极限)的机制，这归因于端粒缩短和有丝分裂磨损。在先前的支持期(R01 CA111365)中，我们发现了一种新的细胞衰老模式(时序寿命)，它独立于有丝分裂磨损和端粒酶活性。我们将按时间顺序排列的寿命定义为静止细胞保持重新进入增殖周期并过渡回 宁静。我们的数据表明，分子和药物诱导的锰超氧化物歧化酶(MnSOD)的过度表达抑制了与年龄相关的线粒体损伤的增加，并延长了时间跨度。我们还观察到，MnSOD的过度表达抑制了静止的成纤维细胞刺激邻近上皮癌细胞增殖的能力随年龄的增加。最后，我们最近的初步调查 结果表明，MnSOD诱导的细胞周期调控通路，包括氧化还原敏感的磷酸酶DUSP1和趋化因子CCL5，可以调节人成纤维细胞的时序寿命。这些观察结果现在使我们检验了特定的假设，即MnSOD和ROS(O2.-和H2O2)调节人成纤维细胞的时间跨度，以及它们通过涉及DUSP1和CCL5的对Edox敏感的细胞周期调节通路影响上皮性癌细胞增殖的能力。为了研究这一假说，我们将确定：(A)依赖于MnSOD的DUSP1和CCL5的表达是否调节正常人成纤维细胞的时间跨度；(B)细胞静止和氧化还原敏感的转录后机制调节MnSOD、DUSP1和CCL5的表达；以及(C)静止的成纤维细胞的衰老通过CCL5的分泌调节共培养的上皮性癌细胞的增殖。更好地理解时间序列寿命的氧化还原生物学及其对上皮癌进展的影响将对衰老和癌症研究具有重要意义，因为这些知识可以极大地促进基于营养和抗氧化剂的新方法的发展，以促进健康老龄化和抑制与年龄相关的癌症进展。

DESCRIPTION (provided by applicant): Cancer incidence increases exponentially with age, suggesting that a common mechanism contributes to both of these biological processes. One such mechanism is thought to be oxidative stress, due to an imbalance between the production of reactive oxygen species (ROS, e.g. O2.- and H2O2, arising from O2 metabolism), and their removal by the antioxidant network. A majority of aging-research is focused on understanding the mechanisms regulating replicative lifespan (Hayflick limit), which is attributed to telomere shortening and mitotic attrition. In the previous period of support (R01 CA111365), we discovered a novel mode of cellular aging (chronological lifespan), which is independent of both mitotic attrition and telomerase activity. We define chronological lifespan as the duration in which quiescent cells retain their capacity to re-enter the proliferative cycle and transit back to quiescence. Our data show that molecular and pharmacologically induced overexpression of manganese superoxide dismutase (MnSOD) suppresses age-associated increase in mitochondrial injury, and extends chronological lifespan. We also observed that MnSOD overexpression inhibits age-associated increases in the ability of quiescent fibroblasts to stimulate the proliferation of neighboring epithelial cancer cells. Finally, our recent preliminary results suggest that MnSOD-induced regulation of cell cycle regulatory pathways including the redox-sensitive phosphatase, DUSP1, and the chemokine, CCL5, could mediate chronological lifespan in human fibroblasts. These observations have now led us to test the specific hypothesis that MnSOD and ROS (O2.- and H2O2) regulate the chronological lifespan of human fibroblasts as well as their ability to influence the proliferation of epithelial cancer cells via edox-sensitive cell cycle regulatory pathways involving DUSP1 and CCL5. To investigate this hypothesis we will determine if: (a) MnSOD dependent expression of DUSP1 and CCL5 regulates the chronological lifespan of normal human fibroblasts; (b) cellular quiescence and redox-sensitive post-transcriptional mechanisms regulate MnSOD, DUSP1, and CCL5 expression; and (c) the aging of quiescent fibroblasts regulates the proliferation of epithelial cancer cells in co-cultures via the secretion of CCL5. A better understanding of the redox-biology of chronological lifespan and its effect on epithelial cancer progression will be of significance to aging and cancer research because this knowledge can greatly facilitate the development of novel nutritional and antioxidant-based approaches to promote healthy aging and suppress age-related cancer progression.