Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA; Systems Biology Institute, Yale University, New Haven, CT, USA; Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, USA.
Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA; Systems Biology Institute, Yale University, New Haven, CT, USA; Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, USA Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA; Systems Biology Institute, Yale University, New Haven, CT, USA; Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, USA Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA; Systems Biology Institute, Yale University, New Haven, CT, USA; Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, USA
Evol Med Public Health. 2014 Oct 15;2014(1):136-45. doi: 10.1093/emph/eou022.
Cancer metastasis is an invasive process that involves the transplantation of cells into new environments. Since human placentation is also invasive, hypotheses about a relationship between invasive placentation in eutherian mammals and metastasis have been proposed. The relationship between metastatic cancer and invasive placentation is usually presented in terms of antagonistic pleiotropy. According to this hypothesis, evolution of invasive placentation also established the mechanisms for cancer metastasis. Here, in contrast, we argue that the secondary evolution of less invasive placentation in some mammalian lineages may have resulted in positive pleiotropic effects on cancer survival by lowering malignancy rates. These positive pleiotropic effects would manifest themselves as resistance to cancer cell invasion. To provide a preliminary test of this proposal, we re-analyze data from Priester and Mantel (Occurrence of tumors in domestic animals. Data from 12 United States and Canadian colleges of veterinary medicine. J Natl Cancer Inst 1971; 47: :1333-44) about malignancy rates in cows, horses, cats and dogs. From our analysis we found that equines and bovines, animals with less invasive placentation, have lower rates of metastatic cancer than felines and canines in skin and glandular epithelial cancers as well as connective tissue sarcomas. We conclude that a link between type of placentation and species-specific malignancy rates is more likely related to derived mechanisms that suppress invasion rather than different degrees of fetal placental aggressiveness.
癌症转移是一种侵袭性过程，涉及细胞向新环境的移植。由于人类胎盘也是侵袭性的，因此提出了关于真兽类哺乳动物侵袭性胎盘与转移之间关系的假说。转移性癌症与侵袭性胎盘之间的关系通常以拮抗多效性来表示。根据这一假说，侵袭性胎盘的进化也为癌症转移建立了机制。相比之下，在这里我们认为，一些哺乳动物谱系中侵袭性胎盘的二次进化可能通过降低恶性肿瘤率对癌症存活产生了积极的多效性影响。这些积极的多效性影响将表现为对癌细胞侵袭的抵抗力。为了初步检验这一假说，我们重新分析了 Priester 和 Mantel（家畜肿瘤的发生。来自美国和加拿大 12 所兽医学院的数据。J Natl Cancer Inst 1971；47：：1333-44）关于奶牛、马、猫和狗的恶性肿瘤率的数据。我们的分析发现，胎盘侵袭性较弱的马科动物和牛科动物，在皮肤和腺体上皮癌以及结缔组织肉瘤中，转移性癌症的发病率低于猫科动物和犬科动物。我们得出的结论是，胎盘类型与物种特异性恶性肿瘤率之间的联系更可能与抑制侵袭的衍生机制有关，而不是与胎儿胎盘侵袭性的不同程度有关。
