The Combination of Three Natural Compounds Effectively Prevented Lung Carcinogenesis by Optimal Wound Healing

The tumor stroma has been described as “normal wound healing gone awry”. We explored whether the restoration of a wound healing-like microenvironment may facilitate tumor healing. Firstly, we screened three natural compounds (shikonin, notoginsenoside R1 and aconitine) from wound healing agents and evaluated the efficacies of wound healing microenvironment for limiting single agent-elicited carcinogenesis and two-stage carcinogenesis. The results showed that three compounds used alone could promote wound healing but had unfavorable efficacy to exert wound healing, and that the combination of three compounds made up treatment disadvantage of a single compound in wound healing and led to optimal wound healing. Although individual treatment with these agents may prevent cancer, they were not effective for the treatment of established tumors. However, combination treatment with these three compounds almost completely prevented urethane-induced lung carcinogenesis and reduced tumor burden. Different from previous studies, we found that urethane-induced lung carcinogenesis was associated with lung injury independent of pulmonary inflammation. LPS-induced pulmonary inflammation did not increase lung carcinogenesis, whereas decreased pulmonary inflammation by macrophage depletion promoted lung carcinogenesis. In addition, urethane damaged wound healing in skin excision wound model, reversed lung carcinogenic efficacy by the combination of three compounds was consistent with skin wound healing. Further, the combination of these three agents reduced the number of lung cancer stem cells (CSCs) by inducing cell differentiation, restoration of gap junction intercellular communication (GJIC) and blockade of the epithelial-to-mesenchymal transition (EMT). Our results suggest that restoration of a wound healing microenvironment represents an effective strategy for cancer prevention.

肿瘤间质（tumor stroma）被描述为“失常的正常伤口愈合过程”。本研究旨在探究伤口愈合样微环境的重塑是否可促进肿瘤愈合。首先，本研究从伤口愈合制剂中筛选出三种天然化合物：紫草素（shikonin）、三七皂苷R1（notoginsenoside R1）及乌头碱（aconitine），并评估了伤口愈合微环境在限制单剂诱导致癌及两阶段致癌中的功效。结果显示，单一使用这三种化合物虽可促进伤口愈合，但发挥伤口愈合功效的效果不佳；而三种化合物联合使用可弥补单剂在伤口愈合中的缺陷，实现最优的伤口愈合效果。尽管单独使用这些化合物可预防癌症，但它们对已形成的肿瘤并无治疗效果。然而，三种化合物联合给药几乎完全抑制了乌拉坦（urethane）诱导的肺致癌过程，并降低了肿瘤负荷。与既往研究不同，本研究发现乌拉坦诱导的肺致癌作用与肺损伤相关，且该过程不依赖肺部炎症。脂多糖（LPS）诱导的肺部炎症并未增加肺致癌风险，而通过巨噬细胞耗竭降低肺部炎症反而促进了肺致癌过程。此外，乌拉坦可损伤皮肤切除伤口模型中的伤口愈合过程；三种化合物联合给药对肺致癌作用的逆转效果，与皮肤伤口愈合的恢复情况一致。进一步研究发现，三种化合物联合给药可通过诱导细胞分化、恢复间隙连接细胞间通讯（gap junction intercellular communication，GJIC）并阻断上皮间质转化（epithelial-to-mesenchymal transition，EMT），减少肺癌干细胞（cancer stem cells，CSCs）的数量。本研究结果表明，重塑伤口愈合样微环境是一种有效的癌症预防策略。